2.2

Question 1

what does a bacterial cell wall being hypertonic mean

Answer 1

water moves into the cell via osmosis as it has higher water potential than outside the cell

Question 2

why do bacteria cells need a cell wall

Answer 2

prevents swelling & bursting
maintains shape
gives support
protection

Question 3

what are bacteria walls mostly made of

Answer 3

peptidoglycan

Question 4

what does a capsule do

Answer 4

protects bacterium from phagocytes
covers cell markers (makes bacteria harder to identify)
may help them survive dry conditions

Question 5

what are pili and why do bacteria need them

Answer 5

thread - like projections needed to attach to host cell for sexual reproduction

Question 6

why do pili make bacteria more vunerable to virus infections

Answer 6

can be used as an entry point

Question 7

what is the structure of a flagellum and how does it move a cell

Answer 7

many stranded helix of protein flagellin
moves via rapid rotations

Question 8

what are the known as mesosomes potentially used for

Answer 8

artefact from preparing cell for electron micrograph
associated with enzyme activity during separation of DNA & cross walls forming

Question 9

what may other infoldings in a bacteria cell be used for

Answer 9

photosynthesis

Question 10

explain plasmids in bacteria

Answer 10

small circles of DNA
reproduce without nucleoid
transferred from one bacterium to another (sexual reproduction)

Question 11

what is a nucleoid in bacterium

Answer 11

single length of DNA not contained in a membrane
DNA is tangled

Question 12

what ribosomes do bacteria have

Answer 12

70s (50s + 30s)
smaller

Question 13

what is gran staining used for

Answer 13

distinguishing gram positive & gram negative bacteria

Question 13

explain how gram staining effects gram positive bacterium

Answer 13

iodine gets trapped in thick peptidoglycan layer
doesn’t decolour when dehydrated with alcohol doesn’t pick up red safranin counter stain
left purple/blue colour

Question 14

what are some differences between gram + & gram - bacterial cell walls

Answer 14

gram (+)
thicker peptidoglycan layer
teichonic acid
plasma membrane
gram (-)
thich middle peptidoglycan layer
outer & inner membrane lipopolysaccharides

Question 15

explain how gram staining effects gram negative bacteria

Answer 15

dehydrated in ethanol dissolves lipopolysaccharide so peptidoglycan exposed iodine washed out therefore take up red safranin counter stain

Question 16

overall how do antibiotics work

Answer 16

target bacterial cell walls & 70s ribosomes

Question 17

how do beta - lactam antibiotics work

Answer 17

inhibit formation of peptidoglycan layer
<effect of gram (+)
>effect on gram (-)

Question 18

how do glycopeptide antibiotics effect bacteria

Answer 18

large polar molecules
<effect on gram (+)
cannot penetrate outer membrane layer of gram (-) bacteria

Question 19

how do polypeptide antibiotics effect bacteria

Answer 19

interact with phospholipids of the outer membrane
<effect on gram (-)
X effect on gram (+)

Question 20

how do other antibiotics effect both bacteria equally

Answer 20

target processes such as protein synthesis carried out by 70s ribosomes

Question 21

how can you classify bacteria

Answer 21

• shape
  -respiratory requirements
• gram +/-

Question 22

state the 4 shapes of bacteria

Answer 22

spherical (cocci)
rod-shaped (bacillic)
twisted (spirilla)
comma-shaped (vibrious)

Question 23

explain the 3 respiratory requirements of bacteria

Answer 23

obligate aerobes - need oxygen
facultative -anaerobes fine with/without oxygen
obligate anaerobes - cannot have oxygen

Question 24

roughly how big are viruses

Answer 24

0.02micrometers - 0.3 micrometers

Question 25

what parts do all viruses have

Answer 25

genetic material capsid receptors

Question 26

what is a capsid made of

Answer 26

repeating protein units known as capsomeres

Question 27

what is the role of VAPs (virus attachment particles)

Answer 27

attach viruses to their host cell

Question 28

give examples of DNA viruses

Answer 28

small pox lambda phage

Question 29

what are bacteriophages

Answer 29

viruses which infect bacteria

Question 30

are DNA viruses or RNA viruses more likely to mutate

Answer 30

RNA more steps in replication

Question 31

what type of virus is the immunodeficiency virus

Answer 31

RNA retrovirus

Question 32

name a positive ssRNA virus

Answer 32

tobacco mosaic virus

Question 33

name a negative ssRNA virus

Answer 33

ebola

Question 34

what viruses always have a protein capsid and lipid envelop

Answer 34

retroviruses

Question 35

why are viruses not classed as living

Answer 35

they cannot reproduce on their own

Question 36

what happens when a virus is taken in via endocytosis

Answer 36

host cell then digests capsid releasing genetic material

Question 37

what is the most common way that viruses infect cells

Answer 37

viral envelop fuses with host cell surface releasing viral genetic material into cell

Question 38

how do viruses often get into plant cells

Answer 38

vectors insects pierce cell wall

Question 39

what does non-virulent & virulent mean

Answer 39

non virulent- not disease causing virulent - disease causing

Question 40

what occurs in the lytic pathway

Answer 40

viral genetic material is replicated independently of the host DNA

Question 40

what is a provirus and when is it formed

Answer 40

the DNA thats inserted into the host cell during the lysogenic cycle

Question 41

When can viruses in the lysogenic state be activated

Answer 41

- host is damaged - repressor/ protein decreases

Question 42

how do positive ssRNA viruses replicate

Answer 42

genetic material enters cell single sense stand used directly as mRNA translated by ribosomes into viral proteins

Question 43

how do negative ssRNA viruses reproduce

Answer 43

genetic material enters cell circus imports RNA replicase antisense strand transcribed to sense stand by RNA replicate free bases act as mRNA transcribed by ribosomes into viral proteins

Question 44

what enzymes are needed in reproduction of retro viruses

Answer 44

reverse transcriptase integrase

Question 45

how do viral particles leave the host cell in the reproduction of retroviruses

Answer 45

exocytosis

Question 46

how do viruses cause symptoms of disease

Answer 46

lysis of host cell release their own lysosomes digest themselves produce toxins

Question 47

why are virus infections often specific to particular tissues

Answer 47

due to the presence of absence of cell markers on host cells viruses can only bind to particular markers

Question 48

who does foot & mouth disease effect

Answer 48

coven-hoofed animals

Question 49

how is foot & mouth disease spread

Answer 49

body secretions (milk) food & water contact with diseased animals

Question 50

how is ebola spread

Answer 50

bodily fluids and blood direct contact

Question 51

how do antiviral treatments work

Answer 51

target receptors target enzyme for translation or replication of DNA/RNA inhibit protease enzyme

Question 52

what do antiviral treatments do

Answer 52

reduce the time a persons sick delay development of symptoms